[grivera]

Interesting video - gotta go to about 1/3 into it for his reasoning: https://m.youtube.com/watch?v=Kgd3pJlM_ps

[chuckies76ta]

Thanks for posting. Very interesting. I like the skit at the end of video.. lol

[Half-Inch Stud]

UT calls the MFG constraint (of cast steel rods) a "design flaw" whereas it was a corporate edict to be the performance constraint.

Think about it: Chevy being the cheapest vehicle line gets forged cranks & rods, whereas PMD leading the 1960s SALES RECORDS was constrained to cast crank & rods.

Was no wonder to me back in the 80s to why every production V8 was "design-limited" to 150% of stock HP, by virtue of block thinning in key zones, or oil delivery.

Bad enough that all the heads had "exhaust crossover" which super-heated the headgasket zone, and carb. Seemed benign when in put-put but Overkill when getting along with extended foot pedal.

Overall, the BOP 10-bolt rear constraint is a laugh, whereas GM's 12- bolt was top-shelf. Dana60 being just right. Nowadays the rear are much more stout for less TQ and HP in SUVs, flyweight mustangs, and the 90s Towncars, Continentals, etc.

Is why we make the modifications.

[track73]

To me Chevrolet’s lighter rotating assembly and light weight block plus their cylinder head design were the reason people raced them instead of Pontiacs on the short tracks.. And I’ve been a Pontiac fan since Fireball Roberts won races in the 60’s. However, I’ve owned Pontiacs but raced Chevies

[PAUL K]

Pontiac started out with forged rods and crankshafts. They were replaced with stronger cast rods and crankshafts for all the non-performance engines. Pontiac's cast crank have held up in builds producing over 1,000 horsepower. I haven't watched the video yet but from the comments above it seems like the cast crank and rod situation may be mentioned.

[mgarblik]

Watched the video. Always loved the way Tony pronounces Pon T ac. I agree with some of his points, but not his conclusion. Agree EVERY domestic engine design of the era, or any era, has some weak points, he calls design flaws. My list could be a mile long, but lets talk about Pontiacs. Pontiac connecting rods are a weak link, yes. Design flaw?, no. If they were a design flaw, they would be failing in "normal use and service", which they didn't. A n example of a "design flaw" would be a Takata air bag. It blows up and kills you in normal use and service. A Pontiac cast rod is just fine to 5800 RPM's in a 400 or 5500 RPM's in a 428-455 indefinitely at 500 HP. But at high HP levels, when something fails, it will be the connecting rods, I agree with that. Is that the reason the aftermarket abandoned Pontiac? I don't know. I think Tony's conclusion is mostly speculation. If the rods were the single problem, that was so easily fixed, with you guessed it, a good set of aftermarket connecting rods. And they were available too. Pontiac people were just too cheap to buy them. Or the prices were just out of reach, and didn't need to be. Carillo, Manley, Crower, Oliver, Childs and Albert and many other AMERICAN companies were in business in the 1960's and could have very easily made rods available for Pontiacs. So just not sure the whole theory really makes sense. Pontiac cast rods were among the worst ever installed in a performance minded engine package. I will concede that.

[tom s]

I have read about the crap cast rods for years.Was it really the rods or was it maybe the “just enough” quality of rod bolts?I submit pics of a pretty catastrophic failure in one of my past engines on the highway in AZ just driving down the road.This rod although be bent did not fail?Tom

[JLMounce]

I catch some of UT's videos from time to time, so I took the opportunity to watch this one. Pretty even handed and I can't say that the rods are THE nail in the coffin, but his point is well reasoned.

We can all wax poetic about whether it was GM that forced the hand or bean counters or a "design flaw". We can even discuss the fact that the rods themselves may not be as big of an issue as the hardware used it them. The net effect however is the same. People fear factory rods in these engines. Justified or not, that is a reality. If the "performance pyramid" concept has any factual basis, by limiting the size of the top of your pyramid, you necessarily limit the bottom of the pyramid as well.

This is an inherent issue with running and umbrella corporation that covers various, but similar brands. There will always be a certain amount of competition between the child companies along with inherent favoritism towards one or a few of them. When you start making decisions for the benefit of one at the detriment of another, it doesn't always work out the way you would hope. In the case of GM, you end up with several companies creating products that are so similar that you eat into your own market share without increasing it. That'll be the death of any brand, aftermarket support or not.

[Sirrotica]

The guys not old enough to really know about what went on in the 60s, The worst thing Pontiac did is not have tight bearing clearances when the cast cranks swelled enough to not have room for oil. Rod bearing spins and the rod starts knocking and breaks the rod. I've done too many autopsies on blown Pontiacs to think the cast rods were the biggest problem in their makeup. They're not a chevy, and everything that works on a chevy, doesn't necessarily work on a Pontiac.

Open the bearing clearances up, and that stops happening. Sorry I don't agree with his hypothesis. He talks about drag racing, which is no where near as hard on the rods as circle track racing is. My engines survived multiple seasons with cast rods, but I also ran looser bearing clearances than stock. Take a used engine right out of a car, throw it into a circle track car with stock clearances, and if you get 2 weeks out of it without spinning a rod bearing, consider yourself very lucky. SBC engine have much smaller rod journals, the cranks don't grow nearly as much with heat, and require less oil as a wedge, and to cool the bearing surfaces. SBCs do blow up, but with all the aftermarket support they're easier, and cheaper to build, and rebuild. I've seen plenty of sbc engines with rods hanging out of the blocks.

He talks about Beswick switching, engine brands, Arnie trailered a bunch of cars that were supposedly superior to his during the 60s. When the 70s came around there were a whole lot of chevy guys that also abandoned the BBC, and installed a hemi in their funny cars. The guy believes he knows what happened back then, but he wasn't there, he read about it somewhere, and listened to the wives tales that have been passed around about why Pontiacs can't cut the mustard in a 12 second car. The worst thing is he's perpetuating the BS stories.

[turbo69bird]

I have t watched the video but it was always GM worried pontiac would out do ****ty Chevy. They always threw the handcuffs on Pontiac and Pontiac always had the best idea men in the game . Bunkie Knudsen John delorean, wanders herb Adams. Left to their own they’d have blown Chevy away. And taken the camaro and corvette down. GM didn’t want brands cannibalizing each other it’s well known . So they protected the corvette and camaro to a lessor extent.

[tom s]

Bean counters have been big issues in all business!How can we make it good enough but make more profit?Save enough dimes and you have saved a million dollars here and a million dollars there.Goes on EVERY day now.Tom

[Half-Inch Stud]

As for racing, a group in North AL started with Pontiacs, then half of em went to the 426 Hemi when it came out, the rest including Butler, stayed with Pontiacs.

[mgarblik]

Pontiac did have a certain love affair with "Armasteel". Produced in large quantities by Central Foundry Division of GM. The name was part of the problem. It's cast iron! Pearlitic , Malleable cast iron. Better properties than gray iron for shafts and bearing caps, but not ideal for a high stress, high speed reciprocating part like a connecting rod. Again, fine for what the engine was designed to do with even a 25% safety factor or a little more. Carefully prepped with a lighter than stock piston, balanced really well and they would live a long happy life even in drag racing applications. Uncle Tony's little anecdote about the blower engine Pontiac blowing up says nothing to me about the quality of the rods or the engine. Maybe it was 4 quarts low on oil?, that would blow it up. Maybe he blew the tires off it showing off and it shot to 9000 RPM's? Maybe he tried to shift and missed a gear?. Maybe he built it with .0015" connecting rod clearance? Who knows. That part of the video has no meaning to me. People do stupid things all the time. Not a good example of a Pontiac "design flaw".

[Sirrotica]

Yes, the so called blown GTO incident proves zero to me, but it will keep getting repeated over, and over. Don and Roy Gay had blown GTO funny cars, with Stratostreak engines running nitro, that beat a lot of brand X cars, so his anecdote carries little weight.

As I said, the guy isn't old enough to have been there during that time period, so any of his information is third hand, at best. The guys that carried the Pontiac banner during that time, weren't blowing engines up every week like he suggests, and they were able to run 12 seconds with cast rods, even though he eludes that it was a feat that could never happen.

His stories have more than a few holes in them.

[BILL BOWMAN1]

I think it was more upper corporate management than connecting rods.

[tom s]

Exactly!Fish stinks from the head.Tom

[J.C.you]

My experience the weak part of cast rods was the big ends would be egged on about 1/2 the cores we tore down. Which would have led to bearing failure then perhaps bolts breaking. Never broke a cast rod in the beam like the guy said. Broke a older steel rod (not sd)that way.

[turbo69bird]

Originally Posted by Sirrotica

Yes, the so called blown GTO incident proves zero to me, but it will keep getting repeated over, and over. Don and Roy Gay had blown GTO funny cars, with Stratostreak engines running nitro, that beat a lot of brand X cars, so his anecdote carries little weight.

As I said, the guy isn't old enough to have been there during that time period, so any of his information is third hand, at best. The guys that carried the Pontiac banner during that time, weren't blowing engines up every week like he suggests, and they were able to run 12 seconds with cast rods, even though he eludes that it was a feat that could never happen.

His stories have more than a few holes in them.

I can tell you that I own the Stephen Pontiac car, I also own a short block they had prepped and sitting on the shelf a friend bought it in the mid 70s from them after they shut down the program. The rods that are in it are similar to the 63 sd rods not cast junk, ( I belive) these were in one of Mc carthys book as mystery rods. Made in 69 but similar to 63 sd rods. So apparently they had some idea that the cast rods were JUNK - and had a Work around for it. Now I can’t say they ever raced this block crank and rods in the car because they raced the. RAII block prepped by merkel that was in the 68 RAII car as far as I know but it shows the spare they had prepped was prepped w forged rods not cast

I’ll
add that the crank in this engine was a 97954. N casting. Not an arma steel .

[Tom Vaught]

Originally Posted by Half-Inch Stud

Overall, the BOP 10-bolt rear constraint is a laugh, whereas GM's 12- bolt was top-shelf. Dana60 being just right.

Is why we make theY modifications.

Not saying parts of the above post are not true, but I blew up three 8.2 posi rears early one and a 12 bolt rear axle,
(as did a 64 GTO owner running a BB Chebby in his car.

You needed the service package axles to help make them live and the other internal parts in the 12 bolt posi units.
Most gave up and ran spools vs continue to buy the Chebby Posi stuff.

Just going by experience.

Tom V.

[turbo69bird]

They ran the 10 bolt BOP rear in the 69 stocker the entire time and never blew it up according to Bill Eckstrom. (This was on 7 inch slicks ) However if you read the article on the 70 - 73 pro stocker (the article that got them kicked out of the racing program) they talk about a special Chevy 12 bolt they had that the gears and posi unit were built for GM by Dana Think it was Jan 72 maybe 73 rodder and super stock. I’d have to look at the magazine again. But it shows they had to run special. Chevy type stuff. The RAM air pan they say in the article was home built for the pro car,
just happens to be identical to the one grumpy Jenkins had on his pro stock car. Hmmmm. I can say that I own that pan and it doesn’t look quite home built to me .
.